Polyarylene sulfide resin composition for electronic parts encapsulation

ABSTRACT

Provided is a polyarylene sulfide resin composition for sealing electronic parts, which comprises (A) from 20 to 35% by weight of a polyarylene sulfide resin, (B) from 60 to 75% by weight of silica, and (C) from 1 to 10% by weight of an elastomer, and contains (D) from 0.05 to 1.2 parts by weight of an epoxysilane and/or (E) from 0.1 to 3 parts by weight of an epoxy resin, both relative to 100 parts by weight of the total amount of the components (A), (B) and (C). The composition has good PCT and TCT acceptable quality and good fluidity, naturally having good properties intrinsic to ordinary PAS resin, and which, when used for sealing electronic parts, causes neither deformation of bonding wires and other elements nor package breakdown, and is therefore favorable to materials for sealing electronic parts.

TECHNICAL FIELD

The present invention relates to a polyarylene sulfide resin compositionfor sealing electronic parts. Precisely, it relates to a polyarylenesulfide (hereinafter often referred to as PAS) resin compositionsuitable for sealing semiconductors such as diodes, transistors, LSIs,CCD devices, ICs, etc.; as well as capacitors, resistors, coils, microswitches, dip switches, etc.

BACKGROUND ART

Polyarylene sulfide resins are engineering plastics having good heatresistance, good flame resistance and good electric and mechanicalproperties, and are known to be widely usable in the field of electronicparts, electric parts, etc., especially as sealants for electronic parts(for example, Japanese Patent Laid-Open Nos. 266461/1986, 296062/1986,150752/1987, 45560/1992, 202245/1993, etc.). In these, however,polyarylene sulfide resins are problematic in that the drivingreliability of the devices with parts sealed with them is not good afterheat cycles.

In general, electronic parts to be sealed include silicon chips, leadframes and others, and are so fabricated that the lead wires therein areelectrically connected with aluminium circuits via bonding wires. Wheresuch electronic parts are sealed with resin such as PAS, generallyemployed is a method of first inserting silicon chips into a mold, andthereafter feeding resin pellets into a screw-in-line typeinjection-molding machine or the like, in which the silicon chips aresealed with the resin.

The matters especially important to the materials to be used for sealingelectronic parts are PCT (pressure cooker test) and TCT (thermal cycletest). In addition, it is also important that the materials for thatpurpose have good fluidity and do not cause package breakdown. Sealantswith poor fluidity will cause deformation or breakdown of bonding wireswhile they are applied to electronic parts through injection molding.

Referring to the prior art techniques, no one has as yet obtainedsealants for electronic parts that satisfy all such fundamentalrequirements.

We, the present inventors have made the present invention, taking theproblems noted above into consideration. The object of the invention isto provide a PAS resin composition which has good PCT and TCT acceptablequality and good fluidity, naturally having good properties intrinsic toordinary PAS resin, and which, when used for sealing electronic parts,does not cause deformation of bonding wires and other elements, and doesnot cause package breakdown as its strength is not lowered. Therefore,the PAS resin composition which the invention is to provide isspecifically favorable to materials for sealing electronic parts.

DISCLOSURE OF THE INVENTION

We, the present inventors have assiduously studied, and, as a result,have found that a polyarylene sulfide resin composition comprisingspecific components can attain the object as above.

Specifically, the invention provides the following:

(1) A polyarylene sulfide resin composition for sealing electronicparts, which comprises (A) from 20 to 35% by weight of a polyarylenesulfide resin, (B) from 60 to 75% by weight of silica, and (C) from 1 to10% by weight of an elastomer, and further contains (D) from 0.05 to 1.2parts by weight, relative to 100 parts by weight of the total amount ofthe components (A), (B) and (C), of an epoxysilane.

(2) A polyarylene sulfide resin composition for sealing electronicparts, which comprises (A) from 20 to 35% by weight of a polyarylenesulfide resin, (B) from 60 to 75% by weight of silica, and (C) from 1 to10% by weight of an elastomer, and further contains (E) from 0.1 to 3parts by weight, relative to 100 parts by weight of the total amount ofthe components (A), (B) and (C), of an epoxy resin.

(3) A polyarylene sulfide resin composition for sealing electronicparts, which comprises (A) from 20 to 35% by weight of a polyarylenesulfide resin, (B) from 60 to 75% by weight of silica, and (C) from 1 to10% by weight of an elastomer, and further contains (D) from 0.05 to 1.2parts by weight of an epoxysilane and (E) from 0.1 to 3 parts by weightof an epoxy resin, both relative to 100 parts by weight of the totalamount of the components (A), (B) and (C).

(4) The polyarylene sulfide resin composition for sealing electronicparts of any one of (1) to (3), wherein the elastomer (C) is anethylenic copolymer of ethylene, an alkyl α,β-unsaturated-carboxylate,and maleic anhydride, with the repetitive units being from 50 to 90% byweight, from 5 to 49% by weight, and from 0.5 to 10% by weight,respectively.

(5) A method for sealing electronic parts with a polyarylene sulfideresin composition, in which the composition comprises (A) from 20 to 35%by weight of a polyarylene sulfide resin, (B) from 60 to 75% by weightof silica, and (C) from 1 to 10% by weight of an elastomer, and furthercontains (D) from 0.05 to 1.2 parts by weight, relative to 100 parts byweight of the total amount of the components (A), (B) and (C), of anepoxysilane.

(6) A method for sealing electronic parts with a polyarylene sulfideresin composition, in which the composition comprises (A) from 20 to 35%by weight of a polyarylene sulfide resin, (B) from 60 to 75% by weightof silica, and (C) from 1 to 10% by weight of an elastomer, and furthercontains (E) from 0.1 to 3 parts by weight, relative to 100 parts byweight of the total amount of the components (A), (B) and (C), of anepoxy resin.

(7) A method for sealing electronic parts with a polyarylene sulfideresin composition, in which the composition comprises (A) from 20 to 35%by weight of a polyarylene sulfide resin, (B) from 60 to 75% by weightof silica, and (C) from 1 to 10% by weight of an elastomer, and furthercontains (D) from 0.05 to 1.2 parts by weight of an epoxysilane and (E)from 0.1 to 3 parts by weight of an epoxy resin, both relative to 100parts by weight of the total amount of the components (A), (B) and (C).

BEST MODES OF CARRYING OUT THE INVENTION

The invention is described in detail hereinunder.

(A) Polyarylene Sulfide Resin

The polyarylene sulfide (PAS) (A) for use in the invention is a polymerhaving repetitive units of a structural formula, —Ar—S— wherein Arindicates an arylene group, in an amount of at least 70 mol %.Typically, it is a polyphenylene sulfide (hereinafter often referred toas PPS) having repetitive units of the following chemical formula (I),in an amount of at least 70 mol %.

wherein R¹ indicates a substituent selected from an alkyl or alkoxygroup having at most 6 carbon atoms, a phenyl group, a group of acarboxylic acid or its metal salt, a nitro group, or a halogen atomincluding fluorine, chlorine and bromine atoms; m indicates an integerof from 0 to 4; and n indicates a degree of polymerization fallingbetween 1.3 and 30.

Depending on the method for producing it, it is known that PAS includestwo types, one having a substantially linear molecular structure withneither branches or crosslinks, and the other having a branched orcrosslinked molecular structure. Any type of PAS is usable in theinvention with no specific limitation.

Preferred PAS for use in the invention is a homopolymer or a copolymerhaving at least 70 mol %, more preferably at least 80 mol % ofrepetitive paraphenylene sulfide units. PAS of which the repetitiveparaphenylene sulfide unit content is smaller than 70 mol % isunfavorable, as it will lose its intrinsic crystallinity characteristicof crystalline polymer and its mechanical properties will be poor. Thecomonomer units for the copolymer polyarylene sulfide include, forexample, metaphenylene sulfide units, orthophenylene sulfide units,p,p′-diphenyleneketone sulfide units, p,p′-diphenylenesulfone sulfideunits, p,p′-biphenylene sulfide units, p,p′-diphenyleneether sulfideunits, p,p′-diphenylenemethylene sulfide units, p,p′-diphenylenecumenylsulfide units, naphthyl sulfide units, etc.

The PAS resin can be obtained in any per-se known method of, forexample, polycondensation of a dihaloaromatic compound with a sulfursource in an organic polar solvent. The melt viscosity of the PAS resinfor use in the invention is not specifically defined, but preferablyfalls between 5 and 100 Pa·s at 300° C. at 200 sec⁻¹.

(B) Silica

Silica has a small linear expansion coefficient, and is used herein forthe purpose of improving the adhesiveness of the composition to chipsand lead frames of electronic parts and also to bonding wires.

The type of silica to be used in the invention is not specificallydefined. For example, herein usable is amorphous silica such as brokensilica, as well as spherical silica such as fused silica or syntheticsilica. Plural types of silica may be blended for use herein. The grainsize and the grain size distribution of silica for use herein are notalso specifically defined. Preferably used is silica having a mean grainsize of at most 50 μm.

Silica for use herein may be previously treated on its surface with asilane coupling agent or the like. The coupling agent for the surfacetreatment is any known one. For example, it includes aminosilanes andepoxysilanes such as γ-aminopropyltrimethoxysilane,N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane,γ-glycidoxypropyltrimethoxysilane,β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, etc.; and alsovinylsilanes, mercaptosilanes, etc.

(C) Elastomer

The elastomer for use in the invention is not specifically defined,including, for example, olefinic elastomers, polyamide elastomers,polyester elastomers, vinyl copolymer elastomers, dienic elastomers,silicone elastomers, etc.

The olefinic elastomers include graft copolymers that may be prepared bygrafting α-olefinic stem polymers with unsaturated carboxylic acids ortheir anhydrides. The α-olefins include polymers and copolymers ofethylene, propylene, butene-1, isobutene, pentene-1, 4-methyl-pentene-1,etc. The unsaturated carboxylic acids and their anhydrides includemaleic acid, fumaric acid, itaconic acid, methylmaleic acid, acrylicacid, methacrylic acid, crotonic acid, citraconic acid, maleicanhydride, methylmaleic anhydride, glycidyl acrylate, etc. Concretely,the olefinic elastomers include ethylenic copolymers from monomers ofethylene, an alkyl α,β-unsaturated carboxylate, and maleic anhydride,with the repetitive monomer units being from 50 to 90% by weight, from 5to 49% by weight, and from 0.5 to 10% by weight, respectively,preferably from 60 to 85% by weight, from 7 to 45% by weight, and from 1to 8% by weight, respectively. The alkyl α,β-unsaturated carboxylateincludes alkyl esters of unsaturated C3-8 carboxylic acids, for example,methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate,n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, methylmethacrylate, ethyl methacrylate, n-propyl methacrylate, isopropylmethacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butylmethacrylate, etc. Preferably, the ethylenic copolymers have MI (asmeasured at 190° C. under a load of 2.16 kg) of from 0.1 to 1000, morepreferably from 0.2 to 500, even more preferably from 1 to 100.

The polyamide elastomers include polyamide block copolymers comprisingpolyamide hard segments coupled with other soft segments. Typically, thesoft segments are, for example, from polyalkylene oxides (in which thealkyl group has from 2 to 6 carbon atoms). The polyamide component forthe hard segments includes, for example, polyamides such as polyamide 6,polyamide 66, polyamide 6-12, polyamide 11, polyamide 12, etc. Thepolyether component for the soft segments includes, for example,polyoxyethylene glycol, polyoxypropylene glycol, polyoxytetramethyleneglycol, etc.

The polyester elastomers include multi-block polymers comprising hardsegments from high-crystalline aromatic polyesters and soft segmentsfrom amorphous polyethers or aliphatic polyesters. The hard segmentsinclude, for example, those from terephthalate-type crystallinepolyesters such as polyethylene terephthalate, polybutyleneterephthalate, polycyclohexanedimethylene terephthalate, etc. The softsegments include, for example, those from aliphatic polyethers such aspolytetramethylene ether glycol, polypropylene glycol, polyethyleneglycol, etc.; and aliphatic polyesters to be prepared from aliphaticdicarboxylic acids such as oxalic acid, malonic acid, succinic acid,glutaric acid, adipic acid, pyromellitic acid, suberic acid, azelaicacid, sebacic acid and the like, and glycols such as ethylene glycol,propylene glycol, butanediol, pentanediol, neopentyl glycol, hexanediol,octanediol, decanediol and the like.

The dienic elastomers include, for example, natural rubbers,polybutadienes, polyisoprenes, polyisobutylenes, neoprenes, polysulfiderubbers, Thiokol rubbers, acrylic rubbers, urethane rubbers, siliconerubbers, epichlorohydrin rubbers, styrene-butadiene block copolymers(SBR), hydrogenated styrene-butadiene block copolymers (SEB, SEBC),styrene-butadiene-styrene block copolymers (SBS), hydrogenatedstyrene-butadiene-styrene block copolymers (SEBS), styrene-isopreneblock copolymers (SIR), hydrogenated styrene-isoprene block copolymers(SEP), styrene-isoprene-styrene block copolymers (SIS), hydrogenatedstyrene-isoprene-styrene block copolymers (SEPS), ethylene propylenerubbers (EPM), ethylene-propylene-diene rubbers (EPDM); core/shell typegranular elastomers such as butadiene-acrylonitrile-styrene core/shellrubbers (ABS), methyl methacrylate-butadiene-styrene core/shell rubbers(MBS), methyl methacrylate-butyl acrylate-styrene core/shell rubbers(MAS), octyl acrylate-butadiene-styrene core/shell rubbers (MABS), alkylacrylate-butadiene-acrylonitrile-styrene core/shell rubbers (AABS),butadiene-styrene core/shell rubbers (SBR), siloxane-containingcore/shell rubbers, e.g., methyl methacrylate-butyl acrylate-siloxanescore/shell rubbers, etc.; modificates as prepared by modifying theserubbers, etc.

They further include polyorganosiloxane rubbers, and preferred arecopolymers as prepared by copolymerizing polyorganosiloxanes withcrosslinking agents. The polyorganosiloxanes include, for example,hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane,decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane,trimethyltriphenylcyclotrisiloxane,tetramethyltetraphenylcyclotetrasiloxane, etc. The crosslinking agentsinclude, for example, trifunctional or tetrafunctional siloxane-typecrosslinking agents such as trimethoxymethylsilane,triethoxyphenylsilane, tetramethoxysilane, tetraethoxysilane,tetrabutoxysilane, etc.

(D) Epoxysilane

The epoxysilane is meant to indicate an epoxy group-having silanecompound. Preferred are silane compounds having at least one epoxy groupand at least one Si—OR group (where R indicates an alkyl group) in onemolecule. R may be an alkyl group having from 1 to 20 carbon atoms, andis preferably an alkyl group having from 1 to 10 carbon atoms.Concretely, the epoxysilane includes γ-glycidoxypropyltrimethoxysilane,β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane,γ-glycidoxypropyltriethoxysilane, etc. The method of adding theepoxysilane to the composition of the invention is not specificallydefined. For example, it may be added to the composition throughintegral blending or the like.

(E) Epoxy Resin

The epoxy resin has one or more epoxy groups, and may be liquid orsolid. It includes glycidylepoxy resins, for example, glycidyl ethers ofbisphenols such as bisphenol A, resorcinol, hydroquinone, pyrocatechol,bisphenol F, 1,3,5-trihydroxybenzene, trihydroxydiphenyldimethylmethane,4,4′-dihydroxybiphenyl, etc., diglycidyl ethers ofhalogenobisphenol-butanediols but not bisphenols, glycidyl esters suchas glycidyl phthalate, etc., glycidylamines such as N-glycidylaniline,etc.; cyclic non-glycidyl epoxy resins such as epoxypolyolefins,dicyclopentadiene-dioxide, etc.; novolak epoxy resins to be prepared byreacting novolak phenolic resins with epichlorohydrin; and theirsubstituents substituted with any of halogens such as chlorine, bromine,etc., alkoxy groups, carboxyl groups, hydroxyl groups, etc. As thenovolak phenolic resins, preferred are those to be prepared throughcondensation of phenols with formaldehyde.

(F) Other Components

The PAS resin composition of the invention may optionally contain anyother components, in addition to the components mentioned above, so faras the additional components do not interfere with the object of theinvention. The additional components include, for example, variousadditives such as inorganic fillers, antioxidants, heat stabilizers,lubricants, colorants, plasticizers, electroconductive agents, etc.;thermoplastic or thermosetting resins such as polyamides, siliconeresins, silicone oils, silicone soils having various functional groups,polyolefins, polyether sulfones, polyphenylene ethers, etc.; pigments,etc.

The inorganic fillers may be granular or powdery ones, and even anyothers. For example, the granular or powdery inorganic fillers includetalc, titanium dioxide, silica not corresponding to the component (B) inthe invention, mica, calcium carbonate, calcium sulfate, bariumcarbonate, magnesium carbonate, magnesium sulfate, barium sulfate,oxysulfates, tin oxide, alumina, kaolin, silicon carbide, glass powder,glass flakes, glass beads, etc.

The inorganic fillers for use herein may be treated on their surfaceswith a coupling agent or the like, for improving their adhesiveness toresin. The coupling agent to be used for that purpose may be selectedfrom silane coupling agents, titanium coupling agents, and other knowncoupling agents.

The amount of the additional components that may be in the compositionmay be suitably determined, without interfering with the object of theinvention.

3. Blend Ratio of the Components Constituting the PAS Resin Compositionof the Invention

The blend ratio of the components constituting the PAS resin compositionof the invention is as follows: In the composition (1), the amount of(A) polyarylene sulfide resin falls between 20 and 35% by weight,preferably between 20 and 30% by weight, that of (B) silica fallsbetween 60 and 75% by weight, preferably between 62 and 73% by weight,and that of (C) elastomer falls between 1 and 10% by weight, preferablybetween 2 and 8% by weight; and the amount of (D) epoxysilane fallsbetween 0.05 and 1.2 parts by weight, preferably between 0.1 and 1.2parts by weight, relative to 100 parts by weight of the total amount ofthe components (A), (B) and (C).

In the composition (2), the amount of (A) polyarylene sulfide resinfalls between 20 and 35% by weight, preferably between 20 and 30% byweight, that of (B) silica falls between 60 and 75% by weight,preferably between 62 and 73% by weight, and that of (C) elastomer fallsbetween 1 and 10% by weight, preferably between 2 and 8% by weight; andthe amount of (E) epoxy resin falls between 0.1 and 3 parts by weight,preferably between 0.3 and 2.5 parts by weight, relative to 100 parts byweight of the total amount of the components (A), (B) and (C).

If desired, the composition may contain both the components (D) and (E).

If the amount of the polyarylene sulfide resin (A) is smaller than 20%by weight, the fluidity of the composition will be low. If so, thecomposition will deform wires when used for sealing electronic parts. Onthe other hand, if the amount of (A) is larger than 35% by weight, thefraction defective in PCT and TCT of the composition will increase. Ifthe amount of the component (B) silica is smaller than 60% by weight,the fraction defective in PCT and TCT of the composition will increase.On the other hand, if the amount of (B) is larger than 75% by weight,the fluidity of the composition will be low. If so, the composition willdeform wires when used for sealing electronic parts. If the amount ofthe elastomer (C) is smaller than 1% by weight, the fraction defectivein PCT and TCT of the composition will also increase. On the other hand,if the amount of (C) is larger than 10% by weight, the strength of thecomposition will be low. If the amount of the epoxysilane (D) is smallerthan 0.05 parts by weight, the strength of the composition will be low,often causing package breakdown when the composition is used for sealingelectronic parts. If, on the other hand, the amount of (D) is largerthan 1.2 parts by weight, the fluidity of the composition will be low,often causing wire deformation when the composition is used for sealingelectronic parts. If the amount of the epoxy resin (E) is smaller than0.1 parts by weight, the strength of the composition will be also low,often causing package breakdown when the composition is used for sealingelectronic parts. If, on the other hand, the amount of (E) is largerthan 3 parts by weight, the fluidity of the composition will be alsolow, often causing wire deformation when the composition is used forsealing electronic parts.

4. Preparation of PAS Resin Composition

The PAS resin composition may be prepared by blending the constituentcomponents mentioned above, optionally along with the additionalcomponents that may be selectively added to the composition. Forexample, the components maybe kneaded in melt to prepare thecomposition.

Kneading the components in melt may be effected in any ordinary knownmanner. Anyhow, the components shall be uniformly mixed and dispersed inthe resin to prepare the intended resin composition. For kneading thecomponents in melt, favorably used is a double-screw extruder, asingle-screw extruder or the like.

The conditions for kneading the components in melt are not specificallydefined. Preferably, however, too high temperatures or too longresidence time shall be evaded so as to prevent the optional componentsfrom being decomposed or foamed. Concretely, the temperature may fallgenerally between 280 and 350° C., but preferably between 285 and 330°C.

The PAS resin composition thus prepared in the manner as above isgenerally granulated or pelletized into pellets or others having desiredshapes or sizes suitable for secondary processing, before it is appliedto molding, especially injection molding.

5. Use for Sealing Electronic Parts

The PAS resin composition of the invention is favorably used forelectronic parts or for sealing electronic parts. The type of theelectronic parts to which the composition is applied is not specificallydefined. For example, the composition is applicable to variouselectronic devices such as integrated circuit devices including, forexample, diodes, transistors, LSIs, CCD devices, ICs, etc., and also tocapacitors, resistors, coils, micro switches, dip switches, etc.

The PAS resin composition of the invention is described more concretelywith reference to the following Examples.

EXAMPLES 1 TO 16, COMPARATIVE EXAMPLES 1 TO 13

Using a Henschel mixer, the components shown in Table 1 and Table 2below were uniformly blended in the ratio indicated in those Tables, andthe resulting blend was kneaded in melt and pelletized into pellets bythe use of a double-screw extruder (Toshiba Machine's TEM35) in whichthe temperature of the cylinder was controlled to fall between 280 and350° C.

In the Tables, the amount of each component is designated as follows:For the components (A), (B), (C), (F) and (G), the amount of eachcomponent is in terms of % by weight relative to 100% by weight of thetotal amount of all these components. For the components (D) and (E),the amount of each component is in terms of parts by weight relative to100 parts by weight of the total amount of the components (A), (B), (C),(F) and (G). The blanks indicate 0 (zero).

<Constituent Components>

Component (A) (PAS)

<1> PPS-1:

833 mols of sodium sulfide hydrate (Na₂S5H₂O), 830 mols of lithiumchloride (LiCl) and 500 liters of NMP were put into a polymerizationreactor equipped with a stirrer, and dehydrated at 145° C. under reducedpressure for 1 hour. Next, the reaction system was cooled to 45° C., and905 mols of dichlorobenzene (DCB) was added thereto, and the monomerswere polymerized at 260° C. for 3 hours. The reaction mixture was washedfive times with hot water, once with N-methyl-2-pyrrolidone (NMP) at170° C., and three times with water, and then dried at 185° C. to obtainPPS-1.

The melt viscosity of PPS-1 was 12 Pa·s at 300° C. at 200 sec⁻¹.

<2> PPS-2:

PPS-2 was prepared in the same manner as above for preparing PPS-1,except that the polymerization time and the number of washing operationswere varied.

Its melt viscosity was 40 Pa·s at 300° C. at 200 sec⁻¹.

<3> PPS-3:

This is Semilinear PPSH1 from Toprene.

Its melt viscosity was 11 Pa·s at 300° C. at 200 sec⁻¹.

<4> PPS-4:

This is Crosslinked PPSK1 from Toprene.

Its melt viscosity was 12 Pa·s at 300° C. at 200 sec⁻¹.

Component (B) (Silica)

<1> Silica 1:

This is FB74 from Denki Kagaku, having a mean grain size of 31.5 μm.

<2>Silica 2:

Silica 1 was treated on its surface with an epoxysilane (D) mentionedbelow to prepare Silica 2.

<3> Silica 3:

This is FB600 from Denki Kagaku, having a mean grain size of 28 μm.

<4> Silica 4:

This is FB6D from Denki Kagaku, having a mean grain size of 6 μm.

<5> Silica 5:

This is Admafine SO-C2 from Admatex, having a mean grain size of 0.5 Mm.

Component (C) (Elastomer)

<1> Elastomer 1:

This is a copolymer of ethylene-ethyl acrylate-maleic anhydride, BondineAX8390 (trade name) from Sumitomo Chemical, having an ethylene contentof 68% by weight, an ethyl acrylate content of 30% by weight and amaleic anhydride content of 2% by weight.

<2> Elastomer 2:

This is a copolymer of ethylene-ethyl acrylate-maleic anhydride, BondineHX8290 (trade name) from Sumitomo Chemical, having an ethylene contentof 85% by weight, an ethyl acrylate content of 13% by weight and amaleic anhydride content of 2% by weight.

<3> Elastomer 3:

This is an epoxy group-having silicone powder, DC4-7051 from Toray-DowCorning Silicone.

(D) Epoxysilane

This is γ-glycidoxypropyltrimethoxysilane, SH6040 from Toray-Dow CorningSilicone.

(E) Epoxy Resin

This is a cresol-novolak epoxy resin, ECN1299 from Ciba-Geigy (having anepoxy equivalent of from 217 to 244).

(F) Glass Fibers (GF)

This is chopped glass JAFT591 from Asahi Fiber Glass.

(G) Calcium Carbonate

This is calcium carbonate P-30 from Shiraishi Industry.

<Evaluation of Physical Properties>

<1> Spiral flow length (SFL):

Using a 30-ton injection-molding machine (from Toshiba Machine),prepared were sample strips having a thickness of 1 mm, for which thecylinder temperature was 320° C., a mold temperature was 135° C. and theinjection pressure was 1000 kg/cm². The length (mm) of the sample flowhaving been injected in that condition was measured, and this indicatesthe spiral flow length of the sample tested. The spiral flow length isan index of the fluidity of the sample to be molded through injectionmolding. Samples having a larger spiral flow length have betterfluidity.

<2> Flexural Strength (unit: MPa): Measured according to ASTMD790.

<3> Wire Deformation:

A resin composition to be tested was applied to a chip with a 250 mmφaluminium bonding wire being attached to the chip vertically to theresin flow, and the chip with the bonding wire was molded through insertmolding whereupon the condition of the wire was macroscopically checked.

Chip samples with no wire deformation were designated by OO; those withminor wire deformation were by O; those with significant wiredeformation were by Δ; and those with great wire deformation were by x.

<4>Percent Defective in PCT (Pressure Cooker Test):

PCT was conducted according to JIS C5030. Precisely, chip samples sealedwith a resin composition to be tested were processed with hot pressuresteam in a pressure cooker at a temperature of 121° C. and a relativehumidity of 100% and under a pressure of 2.02 atmospheres for 500 hours,and the defective chips were counted to obtain the percent defective(%). For evaluating them, the tested chips were immersed in red ink at90° C. for 3 hours, and then dried in air for 24 hours, and theirpackage was opened. The chips stained with red ink were evaluated “bad”.The percent defective in PCT indicates the wet heat resistance of theresin composition tested.

<5> Percent Defective in TCT (Thermal Cycle Test):

TCT was conducted according to JIS C5030. Precisely, chip samples sealedwith a resin composition to be tested were subjected to 300 heat cycles,one heat cycle comprising heating the ship samples at 130° C. for 1 hourfollowed by cooling them at −40° C. for 1 hour, and the defective chipswere counted to obtain the percent defective (%). For evaluating them,the tested chips were immersed in red ink at 90° C. for 3 hours, andthen dried in air for 24 hours, and their package was opened. The chipsstained with red ink were evaluated “bad”. The percent defective in TCTindicates the heat shock resistance of the resin composition tested.

<Test Data>

The test-data are shown in Table 1 and Table 2.

TABLE 1 Example 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 (A) PAS PPS 1 2533 10 20 23 25 22 26 35 35 28 28 29 25 PPS 2 25 PPS 3 27 PPS 4 32 (B)Silica Silica 1 70 66 62 70 55 73 68 62 68 67 65 Silica 2 70 Silica 3 7255 68 62 Silica 4 Silica 5 10 7 (C) Elastomer Elastomer 1 5 2 3 8 5 5 63 3 5 3 3 5 Elastomer 2 7 Elastomer 3 3 5 9 (D) Epoxysilane 0.3 0.6 0.11.2 0.3 0.3 0.5 0.2 0.5 0.3 (E) Epoxy Resin 0.3 1.5 2.5 2.5 1.5 1.0 TestData SFL (mm) 130 101 121 108 134 157 115 102 113 140 131 96 123 111 117127 Flexural Strength (MPa) 57 116 67 51 50 66 78 93 96 99 52 88 65 7461 64 Wire Deformation 00 0 00 0 00 00 0 0 0 00 00 0 00 0 00 00 PercentDefective (%) in 0 5 5 0 0 0 0 0 5 5 0 0 0 10 0 0 PCT Percent Defective(%) in 0 5 5 0 0 0 0 0 5 0 0 0 0 5 0 0 TCT

TABLE 2 Comparative Example 1 2 3 4 5 6 7 8 9 10 11 12 13 (A) PAS PPS118 39 25 24 22 25 29 30 30 30 30 30 PPS2 25 (B) Silica Silica 1 78 57 6462 70 73 70 62 70 70 50 (C) Elastomer Elastomer 1 4 4 11 5 5 5 5 10 5Elastomer 3 14 9 (D) Epoxysilane 0.5 0.3 0.6 0.5 1.5 0.3 0.3 0.5 0.3 (E)Epoxy Resin 4.0 (F) GF 15 60 (G) Calcium Carbonate 70 Test Data SFL (mm)37 214 134 97 43 68 148 153 94 86 115 205 107 Flexural 36 36 38 37 66103 31 40 52 68 102 136 53 Strength (MPa) Wire x ∘∘ ∘∘ Δ x x ∘∘ ∘∘ Δ Δ ΔΔ ∘ Deformation Percent 10 50 0 0 5 0 5 5 40 30 100 100 90 Defective (%)in PCT Percent 10 60 0 0 10 0 0 5 30 30 100 100 70 Defective (%) in TCT

INDUSTRIAL APPLICABILITY

As described hereinabove, obtained is a PAS resin composition which hasgood PCT and TCT acceptable quality and good fluidity, naturally havinggood properties intrinsic to ordinary PAS resin, and which, when usedfor sealing electronic parts, causes neither deformation of bondingwires and other elements nor package breakdown, and is thereforespecifically favorable to materials for sealing electronic parts.

What is claimed is:
 1. A polyarylene sulfide resin composition forsealing electronic parts, which comprises (A) from 20 to 35% by weightof a polyarylene sulfide resin, (B) from 60 to 75% by weight of silica,and (C) from 1 to 10% by weight of an elastomer, and further contains(D) from 0.05 to 1.2 parts by weight, relative to 100 parts by weight ofthe total amount of the components (A), (B) and (C), of an epoxysilane.2. A polyarylene sulfide resin composition for sealing electronic parts,which comprises (A) from 20 to 35% by weight of a polyarylene sulfideresin, (B) from 60 to 75% by weight of silica, and (C) from 1 to 10% byweight of an elastomer, and further contains (E) from 0.1 to 3 parts byweight, relative to 100 parts by weight of the total amount of thecomponents (A), (B) and (C), of an epoxy resin.
 3. A polyarylene sulfideresin composition for sealing electronic parts, which comprises (A) from20 to 35% by weight of a polyarylene sulfide resin, (B) from 60 to 75%by weight of silica, and (C) from 1 to 10% by weight of an elastomer,and further contains (D) from 0.05 to 1.2 parts by weight of anepoxysilane and (E) from 0.1 to 3 parts by weight of an epoxy resin,both relative to 100 parts by weight of the total amount of thecomponents (A), (B) and (C).
 4. The polyarylene sulfide resincomposition for sealing electronic parts as claimed, wherein theelastomer (C) is an ethylenic copolymer of ethylene, an alkylα,β-unsaturated carboxylate, and maleic anhydride, with the repetitiveunits being from 50 to 90% by weight, from 5 to 49% by weight, and from0.5 to 10% by weight, respectively.
 5. A method for sealing electronicparts with a polyarylene sulfide resin composition, comprisingcontacting an electronic part with the polyarylene sulfide resincomposition, wherein the polyarylene sulfide resin composition comprises(A) from 20 to 35% by weight of a polyarylene sulfide resin, (B) from 60to 75% by weight of silica, and (C) from 1 to 10% by weight of anelastomer, and further contains (D) from 0.05 to 1.2 parts by weight,relative to 100 parts by weight of the total amount of the components(A), (B) and (C), or an epoxysilane.
 6. A method for sealing electronicparts with a polyarylene sulfide resin composition, comprisingcontacting an electronic part with the polyarylene sulfide resincomposition, wherein the polyarylene sulfide resin composition comprises(A) from 20 to 35% by weight of a polyarylene sulfide resin, (B) from 60to 75% by weight of silica, and (C) from 1 to 10% by weight of anelastomer, and further contains (E) from 0.1 to 3 parts by weight,relative to 100 parts by weight of the total amount of the components(A), (B) and (C), of an epoxy resin.
 7. A method for sealing electronicparts with a polyarylene sulfide resin composition, comprisingcontacting an electronic part with the polyarylene sulfide resincomposition, wherein the polyarylene sulfide resin composition comprises(A) from 20 to 35% by weight of a polyarylene sulfide resin, (B) from 60to 75% by weight of silica, and (C) from 1 to 10% by weight of anelastomer, and further contains (D) from 0.05 to 1.2 parts by weight ofan epoxysilane and (E) from 0.1 to 3 parts by weight of an epoxy resin,both relative to 100 parts by weight of the total amount of thecomponents (A), (B) and (C).
 8. The polyarylene sulfide resincomposition of claim 1, wherein the polyarylene sulfide resin has atleast 70 mol % of repeat units of formula (I):

wherein R¹ is a substituent selected from the group consisting of analkyl group, an alkoxy group having at most 6 carbon atoms, a phenylgroup, a carboxylic acid group, a metal salt of a carboxylic acid and ahalogen atom; m is an integer of from 0 to 4; and n is a degree ofpolymerization of between 1.3 and
 30. 9. The polyarylene sulfide resincomposition of claim 2, wherein the polyarylene sulfide resin has atleast 70 mol % of repeat units of formula (I):

wherein R¹ is a substituent selected from the group consisting of analkyl group, an alkoxy group having at most 6 carbon atoms, a phenylgroup, a carboxylic acid group, a metal salt of a carboxylic acid and ahalogen atom; m is an integer of from 0 to 4; and n is a degree ofpolymerization of between 1.3 and
 30. 10. The polyarylene sulfide resincomposition of claim 1, wherein the polyarylene sulfide resin has a meltviscosity of 5 to 100 Pa·s at 300° C. of 200 sec⁻¹.
 11. The polyarylenesulfide resin composition of claim 2, wherein the polyarylene sulfideresin has a melt viscosity of 5 to 100 Pa·s at 300° C. of 200 sec⁻¹. 12.The polyarylene sulfide resin composition of claim 1, wherein the silicahas a mean grain size of at most 50 μm.
 13. The polyarylene sulfideresin composition of claim 2, wherein the silica has a mean grain sizeof at most 50 μm.
 14. The polyarylene sulfide resin composition of claim1, wherein the elastomer is selected from the group consisting ofolefinic elastomers, polyamide elastomers, polyester elastomers, vinylcopolymer elastomers, dienic elastomers, and silicone elastomers. 15.The polyarylene sulfide resin composition of claim 2, wherein theelastomer is selected from the group consisting of olefinic elastomers,polyamide elastomers, polyester elastomers, vinyl copolymer elastomers,dienic elastomers, and silicone elastomers.
 16. The polyarylene sulfideresin composition of claim 1, wherein the epoxy silane has at least oneepoxy group and at least one Si—OR group, and R is an alkyl group havingfrom 1 to 20 carbon atoms.
 17. The polyarylene sulfide resin compositionof claim 1, wherein the epoxy silane is selected from the groupconsisting of γ-glycidoxypropyltrimethoxysilane,β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane,γ-glycidoxypropyltriethoxysilane, and mixtures thereof.
 18. Thepolyarylene sulfide resin composition of claim 2, wherein the epoxyresin is selected from the group consisting of glycidyl ethers ofbisphenol A, glycidyl ethers of resorcinol, glycidyl ethers ofhydroxyquinone, glycidyl ethers of pyrocatechol, glycidyl ethers ofbisphenol F, glycidyl ethers of 1,3,5-trihydroxybenzene, glycidyl ethersof trihydroxydiphenyldimethylmethane, glycidyl ethers of4,4′-dihydroxybiphenol, diglycidyl ethers ofhalogenobisphenol-butanediols, glycidyl phthalate, N-glycidylaniline,epoxy polyolefins, dicyclopentadiene-dioxide, novolak epoxy resins, andmixtures thereof.
 19. The polyarylene sulfide resin composition of claim1, further comprising at least one additional component selected fromthe group consisting of inorganic fillers, antioxidants, heatstabilizers, lubricants, colorants, plasticizers, electroconductiveagents, polyamides, silicone resins, silicone oils, functionalizedsilicone oils, polyolefins, polyether sulfones, polyphenylene ethers,and pigments.
 20. The polyarylene sulfide resin composition of claim 2,further comprising at least one additional component selected from thegroup consisting of inorganic fillers, antioxidants, heat stabilizers,lubricants, colorants, plasticizers, electroconductive agents,polyamides, silicone resins, silicone oils, functionalized siliconeoils, polyolefins, polyether sulfones, polyphenylene ethers, andpigments.
 21. The polyarylene sulfide resin composition of claim 1,wherein the amount of the polyarylene sulfide resin is 20 to 30% byweight.
 22. The polyarylene sulfide resin composition of claim 2,wherein the amount of the polyarylene sulfide resin is 20-30% by weight.23. The polyarylene sulfide resin composition of claim 1, wherein theamount of silica is 62 to 73% by weight.
 24. The polyarylene sulfideresin composition of claim 2, wherein the amount of silica is 62 to 73%by weight.
 25. The polyarylene sulfide resin composition of claim 1,wherein the amount of elastomer is 2 to 8% by weight.
 26. Thepolyarylene sulfide resin composition of claim 2, wherein the amount ofelastomer is 2 to 8% by weight.
 27. The polyarylene sulfide resincomposition of claim 1, wherein the amount of epoxy silane is 0.1 to 1.2parts by weight.
 28. The polyarylene sulfide resin composition of claim2, wherein the amount of epoxy resin is 0.3 to 2.5 parts by weight.